Is a photograph showing a senior government official, for example, the Deputy Secretary of Defense, viewing a prototype considered evidence of "public disclosure to the government" which would preclude the subsequent filing of a patent on the prototype?
The relevant question isn't: Was something "disclosed to the government"? Submitting to the USPTO is literally disclosing to the government. Working under confidentiality as a government contractor might involve disclosing to the government.
Who might be documented in a photo as sitting at a table with whom would also not be particularly relevant. What is relevant is whether or not something ready for patenting was offered for sale, was explained, was "used", was entirely under the control of the inventor, was an experimental use, was demonstrated under an understanding of confidentiality, etc. A photo wouldn't usually provide much insight to those issues.